The present invention relates to a semiconductor device and an electronic device, and particularly to a semiconductor device in which power decoupling capacitors comprising chip capacitors are built to reduce switching noise, and a radio or wireless communication device with the semiconductor device built therein, such as a portable cellular phone or the like.
With the speeding-up of a signal processing speed of an electronic device, switching noise offers a problem. Upon the use of a semiconductor device having such a structure as to simultaneously turn on and off a plurality of transistors, power source noise developed due to a power supply variation produced upon switching leads to a malfunction or the like of an electronic device (electronic system) in which the semiconductor device is incorporated. Therefore, a structure has normally been adopted wherein a bypass capacitor for power decoupling is incorporated between a power line and an earth line of an electronic device.
Japanese Published Unexamined Patent Application No. Hei 9(1997)-260537 discloses, for example, a surface-mounting type package wherein chip capacitors are placed over a ceramic substrate to absorb switching noise developed with the speeding-up of a control speed and a signal processing speed of an electronic device.
The ceramic substrate of the package has a solid pattern for power supply and solid patterns for signal wiring and ground as inner layers. The ceramic substrate takes a structure wherein a semiconductor chip is mounted to the surface of the ceramic substrate by using a flip chip structure and chip capacitors are provided on its reverse side or back (on the connecting-surface side of a motherboard).
In the structure wherein the semiconductor chip is mounted to the surface of the wiring board (ceramic substrate) by flip chip bonding and the chip capacitors are attached to the back thereof (the connecting-surface side of the motherboard) as described in the above reference, the inductance and resistance of each wiring portion extending in the direction of thickness of the ceramic substrate increase because the chip capacitors are placed over the back of the ceramic substrate, which is spaced away from electrodes of the semiconductor chip. Therefore, there is a risk of power source noise being incapable of being reduced effectively.
An object of the present invention is to provide a semiconductor device capable of achieving a reduction in switching noise.
Another object of the present invention is to provide an electronic device capable of achieving a reduction in switching noise.
The above, other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
Summaries of typical ones of the inventions disclosed in the present application will be described in brief as follows:
(1) There is provided a semiconductor device in which a main surface of a semiconductor chip is placed over a first main surface of a wiring board so as to be opposed thereto and which includes a plurality of external terminals provided over a second main surface of the wiring board. In the semiconductor device, the plurality of external terminals have a plurality of signal terminals and a plurality of power terminals. The signal terminals are arranged along the periphery of the wiring board and the power terminals are arranged along the inside of a row of the signal terminals. Chip capacitors are placed over the main surface of the semiconductor chip, which lies inside a row of the power terminals. The plurality of signal terminals and power terminals formed over the main surface of the semiconductor chip are connected to a plurality of wires formed over the wiring board respectively. The wiring board is provided with an opening or recess which extends therethrough, and the chip capacitors are located within the opening or recess. Bumps for connecting the electrodes of the chip capacitors and the electrodes of the wiring board, and bumps for connecting the electrodes of the wiring board and the electrodes of the semiconductor chip are simultaneously provided respectively. The electrodes of the semiconductor chip are placed between the signal terminals and the power terminals. A space area, which allows the provision of one or more rows of the signal terminals, is provided between the row of the signal terminals and the row of the power terminals. The chip capacitors are power decoupling capacitors and provided between power terminals and ground terminals formed over the main surface of the semiconductor chip in protruded form. The power decoupling capacitors are provided every predetermined blocks for circuits incorporated into the semiconductor chip.
(2) There is provided an electronic device having wiring board and a semiconductor device connected to electrodes of the wiring board through bumps. The semiconductor device takes the construction of the above means (1). Through holes are defined which are provided with through conductors at portions of the semiconductor device, with which a space area of the wiring board with the semiconductor device attached thereto is faced. Wires drawn for the power terminals are drawn to the reverse side of the wiring board via the through conductors and drawn outside the row of the signal terminals. The semiconductor device constitutes an integrated circuit built in a radio or wireless communication device.
According to the above means (1), (a) since the power decoupling capacitors are directly placed over the main surface of the semiconductor chip, the length of each conductor (wiring) portion lying between each of the capacitors and the semiconductor chip becomes short to thereby allow reductions in resistance and inductance, whereby switching noise can be further reduced.
(b) Since the semiconductor chip having the power decoupling capacitors placed over the main surface thereof is fixed to the wiring board on the main surface side thereof by flip chip bonding, and the wiring board is provided with the opening or recess into which the power decoupling capacitors fixed to the main surface of the semiconductor chip are inserted, a reduction in the thickness of the semiconductor device can be achieved.
According to the above means (2), (a) an electronic device, which provides less switching noise, can be provided owing to the incorporation of the semiconductor device capable of reducing switching noise therein. In particular, a radio or wireless communication device such as a portable cellular phone or the like is capable of providing a more satisfactory call.